overheating neutral link

[sparkymarka]

hi any advise would be helpfull. just looked at a mates fuseboard because he could smell burning everything looked ok untill i spotted the main neutral link bar from the main switch which links the two rcd split loads looked overheated have checked and it seems tight, this only happens when they use the shower 9.5-8.3 kw via a 40amp mcb

 

[pjcomp]

What's the cable from the CU to the shower? If it's a 6mm and a longish cable run that could well come under stress from a 9kw shower, but the 40A MCB is slightly too big for the cable.

PJ

 

[sparkymarka]

hi i think its a 6mm about 3m to shower switch and about 4-5m to shower

 

[ban-all-sheds]

If it's a 6mm and a longish cable run that could well come under stress from a 9kw shower

The longer the cable the less stress it will be under.

 

[spanky]

Have you checked "neutral link bar" is actually in U clamp under main switch as have seen a few where it is not in the clamp and just touching?

Also does main switch feel "gritty" when operated as some times a lack of care during install can lead to crud in switch contacts?

sorry if this is teaching you to suck eggs

 

[sparkymarka]

hi main switch feels fine the neutral seems to be overheating where it connects to the strip at the top of the consumer unit and splits off to feed the two rcd's this is where i find it strange can understand if it was getting hot at the fuse input ? thanks for the input

 

[canduit]

If it's a 6mm and a longish cable run that could well come under stress from a 9kw shower

The longer the cable the less stress it will be under.

I thought the longer the cable is, the higher the resistance would be?

 

[vsynth]

If it's a 6mm and a longish cable run that could well come under stress from a 9kw shower

The longer the cable the less stress it will be under.

I thought the longer the cable is, the higher the resistance would be?

Higher resistance = lower current so the longer the cable the less 'stress' it will be under.

 

[ban-all-sheds]

I thought the longer the cable is, the higher the resistance would be?

It will, therefore the current will be lower, i.e. less "stress".

[edit]Doh! Too slow.... [/edit]

 

[canduit]

Sparkymarka "thinks its a 6mm cable." Would it be wise to confirm this? ie. if the cable csa is too small this could cause the smell?